Mirrors to extend sensor field of view in self-driving vehicles

ABSTRACT

The technology relates to enhancing or extending the field of view of sensors for vehicles configured to operate in an autonomous driving mode. One or more mirrors are used to reflect or redirect beams emitted from onboard sensors that would otherwise be wasted, for instance due to obstruction by a portion of the vehicle or because they are emitted at high pitch angles to the side. The mirrors are also used to redirect incoming beams from the external environment toward one or more of the onboard sensors. Using mirrors for such redirection can reduce or eliminate blind spots around the vehicle. A calibration system may be employed to account for mirror movement due to vibration or wind drag. Each mirror may be a front surface mirror. The mirrors may be positioned on the vehicle body, on a faring, or extending from a sensor housing on the vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/396,176, filed Apr. 26, 2019, the entire disclosure of which isincorporated herein by reference.

BACKGROUND

Autonomous vehicles, such as vehicles that do not require a humandriver, can be used to aid in the transport of trailered (e.g., towed)cargo, such as freight, livestock or other items from one location toanother. Other types of articulated vehicles may also transport cargo orpassengers. Such vehicles may operate in a fully autonomous mode withoutany in-vehicle passenger input or a partially autonomous mode where aperson may provide some driving input. One or more sensors can be usedto detect nearby objects in the environment, and the vehicle may useinformation from the sensors when driving in an autonomous mode.Depending on the size, shape and orientation of the vehicle, there maybe one or more blind spots around the vehicle. Blind spots may bereduced by adding more sensors. However, each added sensor results inincreased cost and may increase computer processing power requirements.Also, this approach may not be physically feasible in certain instances.

BRIEF SUMMARY

All vehicles have blind spots that may impair the field of view (FOV) ofthe driver or on-board computer system in the case of a vehicle capableof operating in a self-driving mode. Large-sized vehicles such as cargovehicles, buses and construction equipment can encounter particularchallenges compared to smaller passenger vehicles such as sedans orvans. For instance, the trailer of a cargo truck may obstruct the FOV ofsensors mounted on the truck's tractor, especially during a turningmaneuver. And due to the size of the truck, the blind spot(s) may besignificantly larger than those of a smaller passenger vehicle.

Careful sensor placement can help to reduce blind spots. Employingadditional sensors on the vehicle can further minimize blind spots.However, adding sensors can increase system cost as well as processingcomplexity, for example from a sensor fusion perspective. Regardless ofthe number or type of added sensors, some areas around the vehicle maybe obscured or have reduced visibility due to physical limitations onwhere the sensors can be placed.

The technology described herein employs one or more reflectivecomponents (mirrors) located external to the sensor to increase thesensor's effective FOV. Such mirrors can reflect or redirect beams thatwould otherwise be wasted. By way of example, the main lidar sensor onthe roof of the tractor of a cargo vehicle may rotate to provide a 360°FOV. As it rotates through various yaw positions, multiple beams areemitted across a set of pitches (e.g., between +2° to −18°). Some beamsmay be wasted due to obstruction by the trailer. Other beams may bewasted because they are emitted at high pitch angles to the side. Usingmirrors to redirect these and other beams emitted from the lidar sensorcan help address the blind spot issue and provide enhanced visibilityaround external obstructions, e.g., a large truck between the vehicleand another object. Depending on the configuration and materials, themirrors may also be employed with other types of sensors (e.g., camerasand radar).

According to one aspect of the technology, a vehicle is configured tooperate in an autonomous driving mode. The vehicle comprises a drivingsystem, a perception system, one or more mirrors and a control system.The driving system includes a steering subsystem, an accelerationsubsystem and a deceleration subsystem to control driving of the vehiclein the autonomous driving mode. The perception system includes one ormore sensors configured to detect objects in an environment surroundingthe vehicle based on obtained sensor data. Each of the sensors isdisposed in a respective housing positioned along the vehicle. The oneor more mirrors are remote from the respective housings of the one ormore sensors. The one or more mirrors are configured to reflect receivedsignals towards at least one of the one or more sensors to enhance asensor field of view. The control system is operatively connected to atleast the driving system and the perception system. The control systemhas one or more computer processors configured to receive sensor datacorresponding to the enhanced sensor field of view from the perceptionsystem and to direct the driving system when operating in the autonomousdriving mode based on the sensor data received from the perceptionsystem.

In one example, the vehicle further comprises a calibration systemconfigured to detect an amount of vibration for the one or more mirrorsand to provide information regarding the detected amount of vibration tothe perception system or the control system during processing of theobtained sensor data. The calibration system may be part of theperception system or the control system.

In another example, the one or more mirrors are further configured toreflect emitted signals from the one or more sensors to the environment.Here, the emitted signals may include laser light or radio waves, andthe received signals may be at least one of laser light, radio waves,optical imagery or infrared imagery.

In another example, the one or more mirrors are planar front surfacemirrors. In a further example, the one or more mirrors are rigidlyaffixed to a surface of the vehicle. In yet another example, a given oneof the one or more mirrors extends externally from the respectivehousing of a corresponding one of the one or more sensors.

In a further example, the one or more mirrors are configured to deployaway from a surface of the vehicle during operation of the vehicle inthe autonomous driving mode. Deployment may include the one or moremirrors popping out from a surface of the vehicle. The vehicle mayinclude a servo mechanism configured to control deployment of the one ormore mirrors. Here, the servo mechanism may be further configured tosteer the one or more mirrors. Alternatively, the servo mechanism isfurther configured to dampen vibration of the one or more mirrors.

In another example, the one or more mirrors includes a first mirror anda second mirror. According to one scenario, the first and second mirrorsmay be non-coplanar.

The vehicle may be a truck having a tractor unit, with the tractor unitincluding a coupling system to pivotally coupled to a trailer. In thiscase, the one or more mirrors may be disposed along respective surfacesof the tractor unit. Alternatively and/or additionally, the vehicleincludes the trailer and at least one of the one or more mirrors isdisposed along the trailer.

According to another aspect, a method of operating a vehicle in anautonomous driving mode comprises receiving, by one or more processorsof a control system of the vehicle, obtained sensor data from one ormore sensors configured to detect objects in an environment surroundingthe vehicle, each of the one or more sensors being disposed in arespective housing positioned along the vehicle and having a respectivefield of view; receiving, by the one or more processors, reflectedsignals from one or more mirrors remote from the respective housings ofthe one or more sensors, the one or more mirrors being configured toreflect received signals towards at least one of the one or more sensorsto provide an enhanced a sensor field of view; and controlling, by theone or more processors, a driving system of the vehicle when operatingin the autonomous driving mode, in response to the received obtainedsensor data and the received reflected signals that provide the enhancedsensor field of view.

The method may further comprise controlling operation of at least one ofthe one or more mirrors by: deploying the at least one mirror away froma surface of the vehicle during operation of the vehicle in theautonomous driving mode; steering the at least one mirror; dampeningvibration of the at least one mirror; and/or retracting the at least onemirror onto or into the vehicle when not in use. The method mayalternatively or additionally further include calibrating the one ormore mirrors prior to or during operation in the autonomous drivingmode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-B illustrate an example tractor-trailer arrangement for usewith aspects of the technology.

FIGS. 1C-D illustrate an example articulated bus arrangement for usewith aspects of the technology.

FIG. 1E illustrates an example passenger vehicle for use with aspects ofthe technology.

FIG. 2A illustrates a system diagram of an autonomous vehicle controlsystem in accordance with aspects of the disclosure.

FIG. 2B illustrates a system diagram of a trailer, in accordance withaspects of the disclosure.

FIG. 2C illustrates a system diagram of another autonomous vehiclecontrol system in accordance with aspects of the disclosure.

FIG. 3A is an example of sensor coverage for a vehicle in accordancewith aspects of the disclosure.

FIG. 3B is another example of sensor coverage for a vehicle inaccordance with aspects of the disclosure.

FIG. 4 illustrates a sensor scanning example in accordance with aspectsof the disclosure.

FIG. 5 illustrates an example of sensor field of view obstruction.

FIGS. 6A-B illustrate a field of view scenario in accordance withaspects of the disclosure.

FIGS. 7A-B illustrate another field of view scenario in accordance withaspects of the disclosure.

FIGS. 8A-B illustrate a further field of view scenario in accordancewith aspects of the disclosure.

FIGS. 9A-B illustrate yet another field of view scenario in accordancewith aspects of the disclosure.

FIGS. 10A-B illustrate an enhanced field of view scenario in accordancewith aspects of the disclosure.

FIGS. 11A-C illustrate another enhanced field of view scenario inaccordance with aspects of the disclosure.

FIG. 12 illustrates a method of operating a vehicle in an autonomousdriving mode in response to an enhanced field of view, in accordancewith aspects of the disclosure.

DETAILED DESCRIPTION

Overview

The technology relates to fully autonomous or semi-autonomous vehicles,including cargo vehicles (e.g., tractor-trailers) and other articulatedvehicles (e.g., buses), construction or farm vehicles, as well aspassenger vehicles (e.g., sedans and minivans). On-board sensors, suchas lidar sensors, are used to detect objects in the vehicle'senvironment. These sensors may also detect the real-time pose of thevehicle. Reflective components (mirrors) are employed to reduce sensorblind spots and enhance sensor FOV. These and other aspects arediscussed in detail below.

FIGS. 1A-B illustrate an example vehicle 100, such as a tractor-trailertruck. The truck may include, e.g., a single, double or triple trailer,or may be another medium or heavy duty truck such as in commercialweight classes 4 through 8. As shown, the truck includes a tractor unit102 and a single cargo unit or trailer 104. The trailer 104 may be fullyenclosed, open such as a flat bed, or partially open depending on thetype of cargo to be transported. The tractor unit 102 includes theengine and steering systems (not shown) and a cab 106 for a driver andany passengers. In a fully autonomous arrangement, the cab 106 may notbe equipped with seats or manual driving components, since no person maybe necessary.

The trailer 104 includes a hitching point, known as a kingpin, 108. Thekingpin 108 is typically formed as a solid steel shaft, which isconfigured to pivotally attach to the tractor unit 102. In particular,the kingpin 108 attaches to a trailer coupling 109, known as afifth-wheel, that is mounted rearward of the cab. For a double or tripletractor-trailer, the second and/or third trailers may have simple hitchconnections to the leading trailer. Or, alternatively, according to oneaspect of the disclosure, each trailer may have its own kingpin. In thiscase, at least the first and second trailers could include a fifth-wheeltype structure arranged to couple to the next trailer.

As shown, the tractor may have one or more sensor units 110, 112disposed therealong. For instance, one or more sensor units 110 may bedisposed on a roof or top portion of the cab 106, and one or more sidesensor units 112 may be disposed on left and/or right sides of the cab106. Sensor units may also be located along other regions of the cab106, such as along the front bumper or hood area, in the rear of thecab, adjacent to the fifth-wheel, underneath the chassis, etc. Thetrailer 104 may also have one or more sensor units 114 disposedtherealong, for instance along a side panel, front, rear, roof and/orundercarriage of the trailer 104. FIGS. 1C-D illustrate an example ofanother type of articulated vehicle 120, such as an articulated bus. Aswith the tractor-trailer 100, the articulated bus 120 may include one ormore sensor units disposed along different areas of the vehicle.

FIG. 1E is a perspective view of an exemplary passenger vehicle 140.Similar to vehicles 100 and 120, the vehicle 140 includes varioussensors for obtaining information about the vehicle's externalenvironment. For instance, a roof-top housing 142 and dome arrangement144 may include a lidar sensor as well as various cameras and/or radarunits. Housing 146, located at the front end of vehicle 140, andhousings 148 a, 148 b on the driver's and passenger's sides of thevehicle may each store a lidar or other sensor. For example, eachhousing 148 may be located in front of the driver's side door. Vehicle140 also includes housings 150 a, 150 b for radar units, lidar and/orcameras also located towards the rear roof portion of the vehicle.Additional lidar, radar units and/or cameras (not shown) may be locatedat other places along the vehicle 140. For instance, arrow 152 indicatesthat a sensor unit may be positioned along the read of the vehicle 140,such as on or adjacent to the bumper. And arrow 154 indicates thatanother sensor unit may be positioned on the undercarriage of thevehicle.

By way of example, as discussed further below each sensor unit mayinclude one or more sensors within one housing, such as lidar, radar,camera (e.g., optical or infrared), acoustical (e.g., microphone orsonar-type sensor), inertial (e.g., accelerometer, gyroscope, etc.) orother sensors.

Example Systems

FIG. 2A illustrates a block diagram 200 with various components andsystems of a vehicle, such as a truck, farm equipment or constructionequipment, configured to operate in a fully or semi-autonomous mode ofoperation. By way of example, there are different degrees of autonomythat may occur for a vehicle operating in a partially or fullyautonomous driving mode. The U.S. National Highway Traffic SafetyAdministration and the Society of Automotive Engineers have identifieddifferent levels to indicate how much, or how little, the vehiclecontrols the driving. For instance, Level 0 has no automation and thedriver makes all driving-related decisions. The lowest semi-autonomousmode, Level 1, includes some drive assistance such as cruise control.Level 2 has partial automation of certain driving operations, whileLevel 3 involves conditional automation that can enable a person in thedriver's seat to take control as warranted. In contrast, Level 4 is ahigh automation level where the vehicle is able to drive withoutassistance in select conditions. And Level 5 is a fully autonomous modein which the vehicle is able to drive without assistance in allsituations. The architectures, components, systems and methods describedherein can function in any of the semi or fully-autonomous modes, e.g.,Levels 1-5, which are referred to herein as “autonomous” driving modes.Thus, reference to an autonomous driving mode includes both partial andfull autonomy.

As shown in the block diagram of FIG. 2A, the vehicle includes a controlsystem of one or more computing devices, such as computing devices 202containing one or more processors 204, memory 206 and other componentstypically present in general purpose computing devices. The controlsystem may constitute an electronic control unit (ECU) of a tractorunit. The memory 206 stores information accessible by the one or moreprocessors 204, including instructions 208 and data 210 that may beexecuted or otherwise used by the processor 204. The memory 206 may beof any type capable of storing information accessible by the processor,including a computing device-readable medium. The memory is anon-transitory medium such as a hard drive, memory card, optical disk,solid state device, tape memory, or the like. Systems may includedifferent combinations of the foregoing, whereby different portions ofthe instructions and data are stored on different types of media.

The instructions 208 may be any set of instructions to be executeddirectly (such as machine code) or indirectly (such as scripts) by theprocessor. For example, the instructions may be stored as computingdevice code on the computing device-readable medium. In that regard, theterms “instructions” and “programs” may be used interchangeably herein.The instructions may be stored in object code format for directprocessing by the processor, or in any other computing device languageincluding scripts or collections of independent source code modules thatare interpreted on demand or compiled in advance. The data 210 may beretrieved, stored or modified by one or more processors 204 inaccordance with the instructions 208. As an example, data 210 of memory206 may store information, such as calibration information, to be usedwhen calibrating different types of sensors, mirrors and other parts ofa perception system.

The one or more processor 204 may be any conventional processors, suchas commercially available CPUs. Alternatively, the one or moreprocessors may be a dedicated device such as an ASIC or otherhardware-based processor, FPGA or the like. Although FIG. 2Afunctionally illustrates the processor(s), memory, and other elements ofcomputing devices 202 as being within the same block, such devices mayactually include multiple processors, computing devices, or memoriesthat may or may not be stored within the same physical housing.Similarly, the memory 206 may be a hard drive or other storage medialocated in a housing different from that of the processor(s) 204.Accordingly, references to a processor or computing device will beunderstood to include references to a collection of processors orcomputing devices or memories that may or may not operate in parallel.

In one example, the computing devices 202 may form an autonomous drivingcomputing system incorporated into vehicle 100. The autonomous drivingcomputing system may be capable of communicating with various componentsof the vehicle in order to perform route planning and drivingoperations. For example, the computing devices 202 may be incommunication with various systems of the vehicle, such as a drivingsystem including a deceleration system 212 (for controlling braking ofthe vehicle), acceleration system 214 (for controlling acceleration ofthe vehicle), steering system 216 (for controlling the orientation ofthe wheels and direction of the vehicle), signaling system 218 (forcontrolling turn signals), navigation system 220 (for navigating thevehicle to a location or around objects) and a positioning system 222(for determining the position of the vehicle).

The computing devices 202 are also operatively coupled to a perceptionsystem 224 (for detecting objects in the vehicle's environment), a powersystem 226 (for example, a battery and/or gas or diesel powered engine)and a transmission system 230 in order to control the movement, speed,etc., of the vehicle in accordance with the instructions 208 of memory206 in an autonomous driving mode which does not require or needcontinuous or periodic input from a passenger of the vehicle. Some orall of the wheels/tires 228 are coupled to the transmission system 230,and the computing devices 202 may be able to receive information abouttire pressure, balance and other factors that may impact driving in anautonomous mode.

The computing devices 202 may control the direction and speed of thevehicle by controlling various components. By way of example, computingdevices 202 may navigate the vehicle to a destination locationcompletely autonomously using data from the map information andnavigation system 220. Computing devices 202 may use the positioningsystem 222 to determine the vehicles location and the perception system224 to detect and respond to objects when needed to reach the locationsafely. In order to do so, computing devices 202 may cause the vehicleto accelerate (e.g., by increasing fuel or other energy provided to theengine by acceleration system 214), decelerate (e.g., by decreasing thefuel supplied to the engine, changing gears (e.g., via the transmissionsystem 230), and/or by applying brakes by deceleration system 212),change direction (e.g., by turning the front or other wheels of vehicle100 by steering system 216), and signal such changes (e.g., by lightingturn signals of signaling system 218). Thus, the acceleration system 214and deceleration system 212 may be a part of a drivetrain or othertransmission system 230 that includes various components between anengine of the vehicle and the wheels of the vehicle. Again, bycontrolling these systems, computing devices 202 may also control thetransmission system 230 of the vehicle in order to maneuver the vehicleautonomously.

As an example, computing devices 202 may interact with decelerationsystem 212 and acceleration system 214 in order to control the speed ofthe vehicle. Similarly, steering system 216 may be used by computingdevices 202 in order to control the direction of vehicle. For example,if the vehicle is configured for use on a road, such as atractor-trailer truck or a construction vehicle, the steering system 216may include components to control the angle of the wheels of the tractorunit to turn the vehicle. Signaling system 218 may be used by computingdevices 202 in order to signal the vehicle's intent to other drivers orvehicles, for example, by lighting turn signals or brake lights whenneeded.

Navigation system 220 may be used by computing devices 202 in order todetermine and follow a route to a location. In this regard, thenavigation system 220 and/or data 210 may store map information, e.g.,highly detailed maps that computing devices 202 can use to navigate orcontrol the vehicle. As an example, these maps may identify the shapeand elevation of roadways, lane markers, intersections, crosswalks,speed limits, traffic signal lights, buildings, signs, real time trafficinformation, vegetation, or other such objects and information. The lanemarkers may include features such as solid or broken double or singlelane lines, solid or broken lane lines, reflectors, etc. A given lanemay be associated with left and right lane lines or other lane markersthat define the boundary of the lane. Thus, most lanes may be bounded bya left edge of one lane line and a right edge of another lane line.

The perception system 224 also includes one or more sensors or othercomponents for detecting objects external to the vehicle such as othervehicles, obstacles in the roadway, traffic signals, signs, trees, etc.For example, the perception system 224 may include one or more lightdetection and ranging (lidar) sensors, acoustical (e.g., microphone orsonar) devices, radar units, cameras (e.g., optical and/or infrared),inertial sensors (e.g., gyroscopes or accelerometers), pressure sensors,and/or any other detection devices that record data which may beprocessed by computing devices 202. The sensors of the perception system224 may detect objects and their characteristics such as location,orientation, size, shape, type (for instance, vehicle, pedestrian,bicyclist, vegetation, etc.), heading, and speed of movement, etc. Theraw data from the sensors (e.g., lidar point clouds) and/or theaforementioned characteristics can sent for further processing to thecomputing devices 202 periodically or continuously as it is generated bythe perception system 224. Computing devices 202 may use informationfrom the positioning system 222 to determine the vehicle's location andthe perception system 224 to detect and respond to objects when neededto reach the location safely, including planning changes to the routeand/or modifying driving operations.

As indicated in FIG. 2A, the perception system 224 includes one or moresensor assemblies 232. Each sensor assembly 232 may include one or moresensors at least partly received in a housing. In one example, thesensor assemblies 232 may be arranged as sensor towers integrated intothe side-view mirrors on the truck, farm equipment, constructionequipment, bus or the like. Sensor assemblies 232 may also be positionedat different locations on the tractor unit 102 or on the trailer 104, asnoted above with regard to FIGS. 1A-B. The computing devices 202 maycommunicate with the sensor assemblies located on both the tractor unit102 and the trailer 104. Each assembly may have one or more types ofsensors such as those described above.

The vehicle 200 also includes one or more mirrors 234, which may be partof the perception system 224 as shown, or which may be separate from theperception system. The mirror(s) 234 is used to reflect a beam anddirect it to or from one or more sensors of the perception system 224.As discussed further below, each mirror may be placed at a particularlocation along the vehicle external to a corresponding sensor assembly.In some instances, the mirror may be rigidly affixed to the vehicle. Inother instances, the mirror may be pivotally or otherwise adjustablyaffixed to the vehicle. Here, the mirror may be raised from a surface orreceptacle of the vehicle when in use, and lowered towards the surfaceor receptacle when not in use. And in still other instances, the mirrormay be coupled to and extend from a sensor assembly.

The autonomous driving computing system may perform calibration ofindividual sensors and their associated mirrors, all sensors in aparticular sensor assembly relative to a commonly used mirror, betweensensors in different sensor assemblies, between multiple mirrors in caseof non-coplanar setups, etc. This may be done using a calibration system236, which may be part of the perception system 224, the computingdevices 202 or some other part of the autonomous driving computingsystem. In one example, the calibration system 236, perception system224, computing devices 202 and other systems may be directly orindirectly connected via a Controller Area Network (CAN bus) of thevehicle.

Also shown in FIG. 2A is a coupling system 238 for connectivity betweenthe tractor unit and the trailer. The coupling system 238 includes oneor more power and/or pneumatic connections 240, and a fifth-wheel 242 atthe tractor unit for connection to the kingpin at the trailer.

FIG. 2B illustrates an example block diagram 250 of a trailer. As shown,the system includes an ECU 252 of one or more computing devices, such ascomputing devices containing one or more processors 254, memory 256 andother components typically present in general purpose computing devices.The memory 256 stores information accessible by the one or moreprocessors 254, including instructions 258 and data 260 that may beexecuted or otherwise used by the processor(s) 254. The descriptions ofthe processors, memory, instructions and data from FIG. 2A apply tothese elements of FIG. 2B.

The ECU 252 is configured to receive information and control signalsfrom the trailer unit. The on-board processors 254 of the ECU 252 maycommunicate with various systems of the trailer, including adeceleration system 262 (for controlling braking of the trailer),signaling system 264 (for controlling turn signals), and a positioningsystem 266 (to assist in determining the location of the trailer). TheECU 252 may also be operatively coupled to a perception system 268 withone or more sensors for detecting objects in the trailer's environment.One or more mirrors may be included as part of the perception system 268or separate from the perception system. A power system 270 (for example,a battery power supply) provides power to local components on thetrailer. Some or all of the wheels/tires 272 of the trailer may becoupled to the deceleration system 262, and the processors 254 may beable to receive information about tire pressure, balance, wheel speedand other factors that may impact driving in an autonomous mode, and torelay that information to the processing system of the tractor unit. Thedeceleration system 262, signaling system 264, positioning system 266,perception system 268, power system 270 and wheels/tires 272 may operatein a manner such as described above with regard to FIG. 2A.

The trailer also includes a set of landing gear 274, as well as acoupling system 276. The landing gear provide a support structure forthe trailer when decoupled from the tractor unit. The coupling system276, which may be a part of coupling system 238, provides connectivitybetween the trailer and the tractor unit. The coupling system 276 mayinclude a connection section 278 (e.g., for power and/or pneumaticlinks) to provide backward compatibility with legacy trailer units thatmay or may not be capable of operating in an autonomous mode. Thecoupling system also includes a kingpin 280 configured for connectivitywith the fifth-wheel of the tractor unit.

While the components and systems of FIGS. 2A-B are described in relationto a tractor-trailer arrangement, as noted above the technology may beemployed with other types of articulated vehicles, such as thearticulate bus 120 of FIGS. 1C-D.

FIG. 2C illustrates a block diagram 290 with various components andsystems of a passenger-type vehicle such as shown in FIG. 1E, configuredto operate in a fully or semi-autonomous mode of operation. Thepassenger-type vehicle may be, e.g., a car, motorcycle, recreationalvehicles, etc. The block diagram 290 shows that the passenger vehiclemay have components and systems that are equivalent to what is shown anddescribed in block diagram 200, for instance to form an autonomousdriving computing system for controlling vehicle 140 of FIG. 1E.

A user interface system 292 may include, e.g., a mouse, keyboard, touchscreen and/or microphone, as well as one or more displays (e.g., a touchscreen display with or without haptic feedback, a heads-up display, orthe like) that is operable to display information to passengers in thevehicle. In this regard, an internal electronic display may be locatedwithin a cabin of vehicle 140 (not shown) and may be used by computingdevices 202 to provide information to the passengers.

Also shown in FIG. 2C is a communication system 294. The communicationsystem 238 may also include one or more wireless connections tofacilitate communication with other computing devices, such as passengercomputing devices within the vehicle, and computing devices external tothe vehicle, such as in another nearby vehicle on the roadway or aremote server system. The wireless connections may include short rangecommunication protocols such as Bluetooth™ or Bluetooth™ low energy(LE), cellular connections, etc. Various configurations and protocolsmay be employed, such as Ethernet, WiFi and HTTPS, for communication viathe Internet, intranets, virtual private networks, wide area networks,local networks, private networks using communication protocolsproprietary to one or more companies, and various combinations of theforegoing.

Example Implementations

In view of the structures and configurations described above andillustrated in the figures, various implementations will now bedescribed.

Information obtained from one or more sensors is employed so that thevehicle may operate in an autonomous mode. Each sensor, or type ofsensor, may have a different range, resolution and/or field of view(FOV).

For instance, the sensors may include a long range, narrow FOV lidar anda short range, tall FOV lidar. In one example, the long range lidar mayhave a range exceeding 50-250 meters, while the short range lidar has arange no greater than 1-50 meters. Alternatively, the short range lidarmay generally cover up to 10-15 meters from the vehicle while the longrange lidar may cover a range exceeding 100 meters. In another example,the long range is between 10-200 meters, while the short range has arange of 0-20 meters. In a further example, the long range exceeds 80meters while the short range is below 50 meters. Intermediate ranges ofbetween, e.g., 10-100 meters can be covered by one or both of the longrange and short range lidars, or by a medium range lidar that may alsobe included in the sensor system. The medium range lidar may be disposedbetween the long and short range lidars in a single housing. In additionto or in place of these lidars, a set of cameras may be arranged, forinstance to provide forward, side and rear-facing imagery. Similarly, aset of radar sensors may also be arranged to provide forward, side andrear-facing data. Other sensors may include an inertial sensor such as agyroscope, an accelerometer, etc.

Examples of lidar, camera and radar sensors and their fields of view areshown in FIGS. 3A and 3B. In example 300 of FIG. 3A, one or more lidarunits may be located in rooftop sensor housing 302, with other lidarunits in side sensor housings 304. In particular, the rooftop sensorhousing 302 may be configured to provide a 360° FOV. A pair of sensorhousings 304 may be located on either side of the tractor unit cab, forinstance integrated into a side view mirror assembly, along a side dooror quarterpanel of the cab, or extending out laterally along one or bothsides of the cab roof. In one scenario, long range lidars may be locatedalong a top or upper area of the sensor housings 302 and 304. The longrange lidar may be configured to see over the hood of the vehicle. Andshort range lidars may be located in other portions of the sensorhousings 302 and 304. The short range lidars may be used by theperception system to determine whether an object such as anothervehicle, pedestrian, bicyclist, etc. is next to the front or side of thevehicle and take that information into account when determining how todrive or turn. Both types of lidars may be co-located in the housing,for instance aligned along a common vertical axis.

As illustrated in FIG. 3A, the lidar(s) in the rooftop sensor housing302 may have a FOV 306. Here, as shown by region 308, the trailer orother articulating portion of the vehicle may provide signal returns,and may partially or fully block a rearward view. Long range lidars onthe left and right sides of the tractor unit have fields of view 310.These can encompass significant areas along the sides and front of thevehicle. As shown, there may be an overlap region 312 of their fields ofview in front of the vehicle. The overlap region 312 provides theperception system with additional or information about a very importantregion that is directly in front of the tractor unit. This redundancyalso has a safety aspect. Should one of the long range lidar sensorssuffer degradation in performance, the redundancy would still allow foroperation in an autonomous mode. Short range lidars on the left andright sides may have different (e.g., smaller) fields of view 314. Aspace is shown between different fields of view for clarity in thedrawing; however in actuality there may be no break in the coverage. Thespecific placements of the sensor assemblies and fields of view ismerely exemplary, and may different depending on, e.g., the type ofvehicle, the size of the vehicle, FOV requirements, etc.

FIG. 3B illustrates an example configuration 320 for either (or both) ofradar and camera sensors in a rooftop housing and on both sides of atractor-trailer vehicle. Here, there may be multiple radar and/or camerasensors in each of the sensor housings 302 and 304. As shown, there maybe sensors in the rooftop housing with front fields of view 322, sidefields of view 324 and rear fields of view 326. As with region 308, thetrailer may impact the ability of the sensor to detect objects behindthe vehicle. Sensors in the sensor housings 304 may have forward facingfields of view 328 (and side and/or rear fields of view as well). Aswith the lidars discussed above with respect to FIG. 3A, the sensors ofFIG. 3B may be arranged so that the adjoining fields of view overlap,such as shown by overlapping region 330. The overlap regions heresimilarly can provide redundancy and have the same benefits should onesensor suffer degradation in performance.

FIG. 4 illustrates a vehicle using sensor assembly to scan for objectsin the environment. The sensor assembly may be, e.g., rooftop sensorhousing 302 of FIG. 3A. The sensor assembly may include one or morelidar, radar, camera or other sensors therein. Solid and dashed linesemanating from the housing indicate examples of individual scans of theenvironment. For instance, 10 (or more or less) individual scans may bemade by a given sensor per scan period. This may include adjusting thesensor's FOV up or down, left or right, e.g., with a motor, servo orother actuator. The individual scans may be selected to cover particularportions of the sensor's FOV or selected regions around the vehicle.

FIG. 5 illustrates a top-down view 500 of an obstructed FOV, forinstance due to a trailer of the vehicle. Here, the sensor (e.g., alidar sensor) may be located on a roof of the vehicle. Only a portion ofthe trailer is shown, as indicated by the dash-dot line towards the rearof the trailer. The sensor's overall FOV 502 may be obstructed bycorners of the trailer, as shown by FOV edges 504. In order to overcomesuch an obstruction, according to one aspect reflective surfaces(mirrors) may be used to redirect emitted light beams or radio wavesfrom a sensor towards the obstructed area. According to another aspect,received light beams, radio waves or imagery are reflected off of themirror(s) towards the sensor. The sensor may have a transmitter portion(e.g., laser, transmit antenna) for emitted light beams or radio wavesand/or a receiver portion (e.g., photodetector, receive antenna, CCD orCMOS image sensor) for received light beams, radio waves or imagery.

In one example, existing mirrors (e.g., side view mirrors) or otherreflective surfaces can be employed. In other examples, one or moremirrors may be distributed at different places along the tractor,trailer or other parts of the vehicle. This could include placing one ormore mirrors along the cab, a fairing on the tractor or trailer,extending from a portion of the sensor housing, etc. Various examplesare shown in FIGS. 6A-B through 9A-B.

For instance, FIGS. 6A-B illustrate a scenario 600 using side-viewmirrors 602 located on either side of the vehicle cab. In this example,the sensor may be a lidar sensor that emits laser light as shown bydashed line 604. One or more beams of the emitted light are directedtoward and reflect off of the mirror 602. The reflected beams, shown bydashed line 606, may be directed toward a blind spot or other areaaround the vehicle. Light received from the environment, as shown bydotted line 608, is reflected off of a mirror 602 and directed towardthe sensor, as shown by dotted line 610. For ease of illustration inthis figure, emitted light is shown reflecting off of the mirror on theleft side of the vehicle while received light is shown reflecting off ofthe mirror on the right side of the vehicle. In operation, each mirrormay be used to emit and/or receive laser light (or RF waves, optical orinfrared imagery, etc.). FIG. 6B illustrates a perspective view 620 ofthe scenario, showing a mirror reflecting the beam (or radio waves)towards and from a blind spot along the rear of the vehicle. Shorterdashed lines 622 illustrate emitted beams (or radio waves) that are notreflected by the mirror but which may be blocked by a portion of thevehicle (e.g., a front or side surface of the trailer).

FIGS. 7A-B illustrate a scenario 700 using mirrors 702 located on orextending from one or more surfaces of the vehicle, such as the cab. Asabove, the sensor may be a lidar sensor that emits laser light as shownby dashed line 704. One or more beams of the emitted light are directedtoward and reflect off of the mirror 702. The reflected beams, shown bydashed line 706, may be directed toward a blind spot or other areaaround the vehicle. Light received from the environment, as shown bydotted line 708, is reflected off of a mirror 702 and directed towardthe sensor, as shown by dotted line 710. Again, for ease ofillustration, emitted light is shown reflecting off of the mirror on theleft side of the vehicle while received light is shown reflecting off ofthe mirror on the right side of the vehicle. In operation, each mirrormay be used to emit and/or receive laser light (or RF waves, optical orinfrared imagery, etc.). FIG. 7B illustrates a perspective view 720 ofthe scenario, showing a mirror reflecting the beam (or radio waves)towards and from a blind spot along the rear of the vehicle. Shorterdashed lines 722 illustrate emitted beams (or radio waves) that are notreflected by the mirror but which may be blocked by a portion of thevehicle (e.g., a surface of the trailer). In this scenario, themirror(s) 702 may be rigidly affixed or otherwise permanently positionedto a surface of the vehicle.

Alternatively, the mirror(s) 702 may be configured to pop up orotherwise extend from the vehicle during use, and retract onto or intothe vehicle when not in use. In one scenario, pop-up mirrors could beused on an as-needed basis, for instance when the perception systemdetermines that a blind spot exists or that a determined blind spotexceeds some threshold size. This would reduce wind drag during typicalvehicle operation. In this case, a mirror could be extended one or morepreset or calculated distances in specific situations. Such pop-upmirrors could also be steerable, for instance via a servo mechanism thatprovides one or more degrees of freedom, e.g., by panning and/or tiltingthe mirror or an arm member that couples the mirror to the vehicle.Here, the servo mechanism could be used to reflect beams toward (orfrom) needed areas of visibility. For example, when the vehicle isdriving in a crowded surroundings, the system can pop up mirrors toreflect high light beams down to the nearby areas. The servo mechanismcould also be used in conjunction with a calibration system to addressvibration-related issues, for instance by dampening vibration of amirror.

FIGS. 8A-B illustrate another scenario 800 using one or more firstmirrors 802 located on or extending from one or more surfaces of thevehicle (e.g., the cab), and one or more second mirrors 804 alonganother part of the vehicle (e.g., a corner or fairing of the trailer).As above, the sensor may be a lidar sensor that emits laser light asshown by dashed line 806. One or more first reflected beams 808 of theemitted light are directed toward and reflect off of the first mirror802. The first reflected beams 808 are then redirected as secondreflected beams 810 by the second mirror 804. The second reflected 808may be directed toward a blind spot or other area around the vehicle.

Light received from the environment, as shown by dotted line 812, isreflected off of second mirror 804 and directed toward the first mirror802 as first reflected beam 814. Then the first reflected beam 814 isdirected toward and reflected off of the first mirror 802 and towardsthe sensor, as shown by dotted line 816. As noted above, in operationeach mirror may be used to emit and/or receive laser light (or RF wavesor optical imagery). FIG. 8B illustrates a perspective view 820 of thescenario, showing a mirror reflecting the beam (or radio waves) towardsand from a blind spot along the rear of the vehicle. Shorter dashedlines 822 illustrate emitted beams (or radio waves) that are notreflected by the mirror but which may be blocked by a portion of thevehicle (e.g., a surface of the trailer). While only first and secondmirrors are shown in this example, one or more additional mirrors mayalso be employed. In this scenario, the mirrors 802 and/or 804 may berigidly affixed or otherwise permanently positioned to a surface of thevehicle. Alternatively, as with mirrors 702, the mirrors 802 and/or 804may be configured to pop up or otherwise extend from the vehicle duringuse, and retract onto or into the vehicle when not in use. In onescenario, such pop-up mirrors could be used on an as-needed basis, forinstance in response to detection of a blind spot or a change in thesize of a blind spot.

And FIGS. 9A-B illustrate yet another scenario 900 using a mirror 902that extends from the sensor housing, e.g., via an extendable ormaneuverable arm 903. In this example, the sensor may be a lidar sensorthat emits laser light as shown by dashed line 904. One or more beams ofthe emitted light are directed toward and reflect off of the mirror 902.The reflected beams, shown by dashed line 906, may be directed toward ablind spot or other area around the vehicle. Light received from theenvironment, as shown by dotted line 908, is reflected off of the mirror902 and directed toward the sensor, as shown by dotted line 910. Inoperation, the mirror 902 may be used to emit and/or receive laser light(or RF waves, optical or infrared imagery, etc.). FIG. 9B illustrates aperspective view 920 of the scenario, showing a mirror reflecting thebeam (or radio waves) towards and from a blind spot along the rear ofthe vehicle. Shorter dashed lines 922 illustrate emitted beams (or radiowaves) that are not reflected by the mirror but which may be blocked bya portion of the vehicle (e.g., a front or side surface of the trailer).

Any combination of mirror configurations according to the above examplesmay be employed according to aspects of the technology.

FIGS. 10A-B illustrate another example that shows an enhancement to thesensor's FOV by reducing a blind spot. FIG. 10A illustrates a firstscenario 1000 with passenger vehicle having a rooftop sensor with a FOV1002. Arrow 1004 represents the lower limit of the FOV, for instance dueto a corner or other portion of the vehicle. As seen in this rear view,a blind spot 1006 is adjacent to a side of the vehicle. FIG. 10Billustrates a second scenario 1010. In this scenario, the base FOV 1002can be enhanced with an added FOV 1012 via mirror 1014. As a result,blind spot 1016 can be made much smaller than initial blind spot 1006(or eliminated entirely).

FIGS. 11A-C illustrate a further example 1100. Here, as shown in FIG.11A, a first vehicle 1102 may be waiting at a stop light. Anothervehicle, such as a cargo truck 1104, may stop behind the first vehicle1102. Due to the size of the truck, the first vehicle may be partly orentirely obscured from view for a vehicle positioned behind the truck.For instance, FIG. 11C illustrates a third vehicle 1106, e.g., apassenger vehicle such as a sedan or minivan, having a sensor FOV 1108.Here, any of the mirror configurations described above may be employedto redirect laser light (or RF waves, optical or infrared imagery, etc.)to enhance the sensor's FOV, as shown by dotted line 1110.

The mirrors may be front surface mirrors (with the reflective surfacebeing above a backing), and may be flat. There should be minimal or norefraction effect in a secondary (e.g., rear) surface of the mirror.Each mirror can be of any size or shape. For instance, a mirror may berectangular, circular or oval in shape, and range in size from a fewsquare centimeters to one square meter or more. In one scenario, thesize of a mirror may be the FOV range times the distance from the lidarto the mirror. Given both values are typically small, the size of mirrormay be in tens of centimeters. If multiple mirrors are used, they do notneed to be the same size.

Various issues may impact the quality of the information provided byemploying redirecting mirrors. For instance, the size, shape and/ordistance of the mirror from the sensor impacts the size or resolution ofthe objects that can the detected. Wind drag, vibration, bugs, dirt,condensation, frost and other factors may also affect the quality of thereceived information. Thus, a cleaning system may be employed to removeor reduce debris. The cleaning system may include a heater element toeliminate condensation or frost.

As noted above, multiple mirrors may be employed to redirect the beams.This could be done with either coplanar mirrors or non-coplanar mirrors.Vibration and other issues may be more pronounced when there aremultiple mirrors involved. A calibration system (e.g., using cameras)could account for mirror movement due to vibration or wind drag.

For instance, an onboard camera of the perception system or other systemof the vehicle can be used to measure the angular position of the mirrorconstantly during operation. Information about the mirror's angularposition may be employed as part of a mirror reflection model, which isused in an overall sensor calibration process.

In one scenario, the calibration process determines an extrinsic matrixC. Here, the vehicle may drive for several miles (or more or less),collecting a series of data (e.g., pose and a lidar point set). Then thesystem solves for the extrinsic matrix C so that when transforming everylidar point set to the world coordinate system, different lidar pointsets should be well aligned at overlapped parts. In order to helpdetermine the extrinsic matrix C, small fiducial markers could be addedon or incorporated into the mirror surface that can be seen in a smallportion of the laser beams hitting the mirror. The measurements from themarkers can used to accurately determine the position and orientationrelative to sensor. For any laser point p in the laser framework. C*p isits coordinates in the world coordinate system. For laser points thatare reflected, a reflection matrix R_(i) (i is the index of mirror) isneeded so that for any reflected laser point p in the laser framework,R_(i)*p is its real position in the laser framework. Therefore, for allthe reflected laser point p in the laser framework, C*R_(i)*p is itsreal position in the world coordinate system.

There are two ways of computing (C*R_(i)), which is the extrinsic matrixfor reflected laser points. One way treats the approach as a normalcalibration task, but selects out only reflected points. In this way,the system can directly determine C*R_(i). In the other way, the systemmeasures all necessary geometry information of the vehicle and themirror, e.g. normal direction, positions of the laser and the mirror.R_(i) is computed based on this measured information. For instance,given the pose of the vehicle and the extrinsic matrix, the system cancompute a transform matrix T which transforms any laser point in thelidar local coordinate system to the world system (lat/long or smoothcoordinates). T=L*C, where L is a localization matrix, and C is theextrinsic matrix. L changes with the vehicle pose, while C is a constantmatrix which the calibration process is aiming at.

To simplify the process, when calibrating the extrinsic matrix forreflected points, the system may only need to collect the lidar pointsshot into the mirror, and feed that information into the processdescribed above.

In some scenarios, a non-planer mirror could be employed to detectwhether there is an object in a general vicinity, although it may bedifficult to determine exactly where the object is or the particulartype of object. For instance, this might approach may be beneficial witha detector located on the underside of the vehicle, which can be used todetermine that a region beneath or adjacent to the vehicle is clearbefore the vehicle starts moving. In one scenario, one or more mirrorsmay be curved. For example, a convex mirror may be used to expand thefield of view and a concave mirror to contract the field of view. For anon-flat (e.g., convex or concave) mirror, the calibration system wouldcalibrate the returned signal from different points on the mirrorindividually. For instance, a look-up table may be created for laserpoints reflected from different spots on the mirror. This is similar tostoring a high resolution mesh of the mirror surface and computing thereflection transform for each single laser point.

FIG. 12 illustrates an example operational method 1200 for a vehicleconfigured to operate in an autonomous driving mode according to theabove techniques. As shown in block 1202, the method includes receivingobtained sensor data from one or more sensors. One or more processors ofthe vehicle's control system are configured to receive the obtainedsensor data. The sensors may be part of a perception system of thevehicle, and are configured to detect objects in an environmentsurrounding the vehicle. Each of the sensors is disposed in a respectivehousing positioned along the vehicle and has a respective field of view.In one example, multiple sensors may be included in the same housing,while in another example different sensors each have their own housing.

At block 1204, reflected signals are received from one or more mirrorsremote from the respective housings of the one or more sensors. Themirrors are configured to reflect received signals towards at least oneof the one or more sensors to provide an enhanced a sensor field ofview. See, e.g., FIG. 11C, including dotted line 1110. Then, at block1206, a driving system of the vehicle is controlled when operating inthe autonomous driving mode. For instance, the processor(s) of thecontrol system may cause the driving system to perform one or moreoperations in response to the received obtained sensor data and thereceived reflected signals that provide the enhanced sensor field ofview. This may include, e.g., altering a current trajectory of thevehicle by turning or changing lanes, increasing or decreasing speed,performing emergency braking, modifying a planned route, etc.

The above approaches enable the onboard computer system to evaluatelidar and other signals reflected off of one or more mirrors external toa sensor housing. The reflected signals can enhance sensor FOV andreduce blind spots around the vehicle. Such information can be used bythe computer system to effectively control the vehicle (e.g., via aplanner module of the computer system), for instance by modifying adriving operation, changing a route, or taking other corrective action.Using mirrors in the manners described above enables perception to bemore complete and increases the utility of sensors (e.g., more FOV forthe same cost). It also allows sensors to be mounted in a potentiallybetter location (e.g., out of harsh areas and other places that may besubject to impact from dirt, debris, etc.). Such approaches also permitthe system to redirect and utilize sensor measurements of a spinninglaser when it sweeps through areas that does not need sensing, e.g.sensor backside that faces the vehicle, returns from the vehicle ortrailer body, and the like.

Unless otherwise stated, the foregoing alternative examples are notmutually exclusive, but may be implemented in various combinations toachieve unique advantages. As these and other variations andcombinations of the features discussed above can be utilized withoutdeparting from the subject matter defined by the claims, the foregoingdescription of the embodiments should be taken by way of illustrationrather than by way of limitation of the subject matter defined by theclaims. In addition, the provision of the examples described herein, aswell as clauses phrased as “such as,” “including” and the like, shouldnot be interpreted as limiting the subject matter of the claims to thespecific examples; rather, the examples are intended to illustrate onlyone of many possible embodiments. Further, the same reference numbers indifferent drawings can identify the same or similar elements. Theprocesses or other operations may be performed in a different order orsimultaneously, unless expressly indicated otherwise herein.

The invention claimed is:
 1. A method of operating a vehicle in anautonomous driving mode, comprising: receiving, by one or moreprocessors of a control system of the vehicle, sensor data obtained fromone or more sensors of a perception system of the vehicle; detecting, bythe one or more processors, a blockage or a change in a field of view ofthe one or more sensors in an area around the vehicle due to anintervening object; in response to detecting the blockage or the changein the field of view due to the intervening object, obtaining, by theone or more processors, sensor data of reflected signals from one ormore mirrors along the vehicle, the one or more mirrors being configuredto reflect received signals towards at least one of the one or moresensors to provide an enhanced sensor field of view beyond theintervening object; and controlling, by the one or more processors, adriving system of the vehicle when operating in the autonomous drivingmode, in response to the received sensor data obtained from the one ormore sensors and the obtained sensor data of the reflected signals thatprovides the enhanced sensor field of view associated with theintervening object.
 2. The method of claim 1, wherein the vehicle is afirst vehicle, and the intervening object is second vehicle that hasmoved in front of the first vehicle.
 3. The method of claim 2, whereinobtaining the sensor data of reflected signals from the one or moremirrors includes adjusting the one or more mirrors to provide theenhanced sensor field of view beyond the second vehicle.
 4. The methodof claim 3, wherein adjusting the one or more mirrors is performed whenthe second vehicle has moved between the first vehicle and a given roaduser.
 5. The method of claim 1, wherein obtaining the sensor data ofreflected signals from the one or more mirrors includes deploying theone or more mirrors away from a surface of the vehicle during operationof the vehicle in the autonomous driving mode.
 6. The method of claim 5,further comprising retracting the one or more mirrors onto or into thevehicle when not being used to provide the enhanced sensor field ofview.
 7. The method of claim 1, further comprising calibrating the oneor more mirrors prior to or during operation in the autonomous drivingmode.
 8. The method of claim 1, further comprising: detecting an amountof vibration for the one or more mirrors; and providing informationregarding the detected amount of vibration to the perception system orthe control system during processing of the obtained sensor data.
 9. Avehicle configured to operate in an autonomous driving mode, comprising:a driving system including a steering subsystem, an accelerationsubsystem and a deceleration subsystem to control driving of the vehiclein the autonomous driving mode; a perception system including one ormore sensors configured to detect objects in an environment surroundingthe vehicle based on obtained sensor data, each of the one or moresensors being disposed in a respective housing positioned along thevehicle; one or more mirrors configured to reflect received signalstowards at least one of the one or more sensors to enhance a sensorfield of view around the vehicle; and a control system operativelyconnected to the driving system and the perception system, the controlsystem having one or more processors configured to: receive the sensordata obtained from one or more sensors of the perception system; detecta blockage or a change in a field of view of the one or more sensors inan area around the vehicle due to an intervening object; in response todetection of the blockage or the change in the field of view due to theintervening object, obtain sensor data of reflected signals from the oneor more mirrors; and control the driving system of the vehicle whenoperating in the autonomous driving mode, in response to the sensor dataobtained from the one or more sensors and the sensor data of thereflected signals.
 10. The vehicle of claim 9, wherein the one or moreprocessors are configured to obtain the sensor data of reflected signalsfrom the one or more mirrors via adjustment of the one or more mirrorsto provide the enhanced sensor field of view beyond the interveningobject.
 11. The vehicle of claim 9, wherein the one or more processorsare configured to obtain the sensor data of reflected signals from theone or more mirrors via deployment of the one or more mirrors away froma surface of the vehicle during operation of the vehicle in theautonomous driving mode.
 12. The vehicle of claim 11, wherein the one ormore processors are further configured to cause retraction of the one ormore mirrors onto or into the vehicle when not being used to provide theenhanced sensor field of view.
 13. The vehicle of claim 9, wherein theone or more processors are further configured to calibrate the one ormore mirrors prior to or during operation in the autonomous drivingmode.
 14. A method of operating a vehicle in an autonomous driving mode,comprising: receiving, by one or more processors of a control system ofthe vehicle, sensor data obtained from one or more sensors of aperception system of the vehicle; identifying a field of view limitationadjacent to a side of the vehicle associated with a given one of the oneor more sensors of the perception system; in response to the identifiedfield of view limitation of the given sensor, obtaining, by the one ormore processors, sensor data of reflected signals from one or moremirrors arranged along a surface of the vehicle, the one or more mirrorsbeing configured to reflect received signals towards at least one of theone or more sensors to enhance the field of view of the given sensor;and controlling, by the one or more processors, a driving system of thevehicle when operating in the autonomous driving mode, in response tothe received sensor data obtained from the one or more sensors and theobtained sensor data of the reflected signals that provides the enhancedsensor field of view.
 15. The method of claim 14, wherein obtaining thesensor data of reflected signals from the one or more mirrors includesadjusting the one or more mirrors to provide the enhanced sensor fieldof view.
 16. The method of claim 14, wherein obtaining the sensor dataof reflected signals from the one or more mirrors includes deploying theone or more mirrors away from a surface of the vehicle during operationof the vehicle in the autonomous driving mode.
 17. The method of claim16, further comprising retracting the one or more mirrors onto or intothe vehicle when not being used to provide the enhanced sensor field ofview.
 18. The method of claim 14, further comprising calibrating the oneor more mirrors prior to or during operation in the autonomous drivingmode.
 19. The method of claim 14, further comprising dampening vibrationof the one or more mirrors during operation in the autonomous drivingmode.
 20. A vehicle configured to operate in an autonomous driving mode,comprising: a driving system including a steering subsystem, anacceleration subsystem and a deceleration subsystem to control drivingof the vehicle in the autonomous driving mode; a perception systemincluding one or more sensors configured to detect objects in anenvironment surrounding the vehicle based on obtained sensor data, eachof the one or more sensors being disposed in a respective housingpositioned along the vehicle; one or more mirrors configured to reflectreceived signals towards at least one of the one or more sensors toenhance a sensor field of view around the vehicle; and a control systemoperatively connected to the driving system and the perception system,the control system having one or more processors configured to: receivesensor data obtained from the one or more sensors of the perceptionsystem; identify a field of view limitation adjacent to a side of thevehicle associated with a given one of the one or more sensors of theperception system; in response to the identified field of viewlimitation of the given sensor, obtain sensor data of reflected signalsfrom the one or more mirrors; and control the driving system of thevehicle when operating in the autonomous driving mode, in response tothe received sensor data obtained from the one or more sensors and theobtained sensor data of the reflected signals.